1. Field of the Invention
The present invention relates to a relax inducing device for inducing a user to a relax state, and particularly a relax inducing device capable of detecting a biological signal of the user such as heartbeat number or respiration number, and controlling an amount of stimulus to be applied to the user according to the biological signal.
2. Disclosure of the Prior Art
In the past, it has been proposed to determine a relax level of a user according to a biological signal such as brain wave or heart rate. For example, Japanese Patent Early Publication [KOKAI] No. 1-131648 discloses to treat values of heartbeat R--R interval defined as a basic period of an electrocardiogram of a user by a high-speed Fourier transform, and determine a relax level index of the user according to a power value of a particular frequency range and a total power value. In addition, Japanese Patent Early Publication [KOKAI] No. 3-272745 discloses to determine an index by calculating a dispersion of the heartbeat R--R interval. Moreover, Japanese Patent Early Publication [KOKAI] No. 5-42129 discloses to detect a respiration signal in addition to a heartbeat signal of a user, and determine a relax level index by calculating a dispersion of at least one of those signals. However, when the dispersion is used as the relax level index, there is a problem that the confidence of the relax level is poor because of individual variations of the users.
As to a relax inducing device such as a massager of providing a stimulus to a user to induce the user into a relax state, it has been known that there are massagers in which a massage motion must be manually adjusted by the user, and a programmed massage motion is provided to the user. In the former massager, there is a problem that the adjusting of the massage motion is troublesome. On the other hand, since the later massager provides the programmed massage motion irrespective of a physical condition of the user, there is a possibility that the user often feels the programmed massage motion uncomfortable.
Thus, there is room for further improvement in the method of determining the relax level index and the relax inducing device.